Process of purifying petroleum oils



Patented Apr. 16, 1'929.

UNITED STATES 1,709,203 PATENT. OFFICE.

JOHN C. BLACK, OF DESTREHAN, LOUISIANA, AND WIRT D. RIAL AND RAYMOND '1.

HOWES, OF WILMINGTON, CALIFORNIA," ASSIGNORS TO PAN AMERICAN PETRO- LEUMCOMPANY, OF LOS ANGELES, CALIFORNIA, A CORPORATION OF CALIFORNIA.

PROCESS OF. PURIFYING PETROLEUM OILS.

No Drawing.

Our invention relates to the treatment of petroleum oils to purify sameand 1t has particular reference to the purlficatlon of petroleumhydrocarbons ofthose substances com- 5. pounds or natural ingredientswhich 1I 1 the presence of water, alkaline or salt solut1ons, tend toemulsify the oil and the prlme object of our invention is treatinghydrocarbon 011s, especially of the western classes, to refine same bythe removalv of emulsifying compounds, such as soap forming compounds,and acids, the presence Of'WlllCl'l 1s the zhief cause for the formationof the undesirable emulsions.

As a general rule emulsifiable compounds in any oil are objectionable,but th 1s 1s especially true of certain lubricating 011s, as turbineoils, which, with admixture of water or aqueous solutions are requlredto reslst emulsification. It has been, and is now, ex-

tremely difi'icult so to refine a western petroleum oil that it willmeet this requirement. There exist in these oils, ingredients, compoundsand substances which lend themselves naturally to emulsification, andvery frequently these emulsions are formed during refining operations.They are extremely d1fficult to destroy or break down and areresponsible for high treating losses and costly 3 equipment tie-ups.

The alcoholic treatment is one that is fre.

quently employed to rectify this condition and remove those naturallyinherent constituents of petroleum oil which bring about this conditionof emulsification. While this alcoholic treatment is satisfactory to alarge degree, it is too expensive for general use, and the essentialpurpose of our invention is to provide an economical process fortreating hydrocarbon oils by which all soap forming compounds'and infact all emulsion producing and forming substances may be wholly removedfrom. the oil. y

We have discovered that it is possible to convert the soap formingcompounds and petroleum acids into a sodium soap and that after a.partial removal of the sodium soap, a final and complete removal of itmay be effected by or in the presence of hydrates of an alkaline earthmetal, in accordance with thesteps as detailed hereinafter.

Lubricating oil is first subjected to a treatment with a relatively weakcaustic soda solution, or approximately 2 to 5'B., and pro- Applicationfiled April 26,

portioned in excess of the quantity needed completely to act with allpetroleum acids or sified conditions of the oil, be they soap formingsubstances or otherwise. Our experience shows that approximately aproportion of ten percentum of the caustic soda solution is enerallycorrect for the purposes mentioned, but it will be understood that .thisproport on may vary according to the amount and to the character of thecompounds or substances or ingredients which are susceptible toemulsification in the particular oil under treatment. So also may thestrength vary in proportion as the character of the oil varies, 1t belnggenerally observed in our experience that the heavier the oil is, themore dilute should be the caustic soda used, its quantity however beingin an inverse ratio.

After having first treated the oil with the caustic soda solution, themixture of the oil and caustic soda solution is subjected to a pressureof from fifty to one hundred pounds, in a closed retort of anyconstruction and preferably insulated to maintain heat, live steam beingemployed to agitate the mixture 1n order to bring about as complete areaction as possible between the caustic soda and the compounds oringredients of the oil, that are to be removed. 1

After sufiicient treating in this manner, the agitation with steam isdiscontinued and the mixture allowed to stratify in accordance with thespecific gravities of the components of the mixture. The aqueous stratumor por t1on of the mixture is then withdrawn, and the oil is subjectedthereupon to hot water washes to remove the caustic soda and the soapforming substances released thereby from their association with the oil.By this treatment a removal of substantially all of the soap, and

soap forming substances is accomplished. 1

scribed. These compounds we have found to remain inthe oil treated asoutlined-in suiiicientquantities to cause an emnlsification of the oilwhenmixed and agitated with aqueous caustic soda, salt or alkalinesolutions. We have discovered that these emulsifying sub stances may beacted upon to form compounds which may be readily removed. For thepurpose of converting these emulsifying agents into compounds which maybe separated from the oil, We find that alkaline earth metal hydroxidesare particularly adaptable, because they combine with or absorb readilythe sodium soap compounds in the oil and other emulsifying constituents,such as gums, resins and other products of polymerization, to form othercompounds which may be readily separated from the oil, and thesealkaline earth metals are available in unlimited quantities atreasonable cost. Of the alkaline earth metal hydroxides, which areusable for the purposes, we prefer calcium in the form of hydrate,though barium hydrate and magnesium hydrate may be employed withsatisfactory results. The alkaline earth metal hydroxide used is mixedwith the oil that has been previously treated for the purificationthereof and still contains the undesirable emulsifying bodies.The-compounds resulting from the action or reaction of the introducedhydrate, which we prefer to be calcium hydrate, in physicalcharacteristics are gelatinous, and being somewhat soluble in the oil,cannot be separated by filtration for this reason. To overcome thisobjection We mix with oil and calcium hydrate'a desirable quantity ofany of the well known filtering clays or infusorial earth, whereby thesaid soaps are extracted by adsorption, i

In practicing the invention, the mixture of oil, (previously treated asexplained), filtering clay, infusorial earth or diatomaceous earth-andcalcium hydrate is subjected to a temperature at which expulsion of thewater content of the mixture occurs. This temperature, we find is'about300 F. When all the water has been driven oif, the mixture is filteredin the manner and by means well known and used in the art, and therebythose compounds which in the oils are naturally contained and act asemulsifiers are eliminated completely. The proportion which the calci umhydrate sustains to the oil treated is substantially as 1 pound to 1gallon of oil, and that of the clay to the oil substantially as 1 poundto 1 gallon of oil. -When these ingredients are admixed with the oil,the resulting I mixture is agitated for a period of time suffi cient tobring about the reaction or adsorption of the calcium hydrate upon thesoaps or soap forming compounds in the oil. While the time required forthis conversion and adsorption of the soap forming ingredi ents to takeplace is dependent upon various conditions, as the quality of the oil,the quantity of emulsifying agents in the oil, etc., it may be statedthat when water no longer is driven off, this is fairly accurateindication that the process-has proceeded long enough to effect thepurposes.

We have 'referred to calcium hydrate as one of the alkaline earth metalhydroxides which is capable of converting and adsorbing the sodium soapnaturally contained or formed in hydrocarbon oil into compounds whichmay readily be separated from the oil. There are other hydrates whichfall within this class of alkaline earth metal hydroxides and which arecapable of effecting the same purposes. Such hydrates are as statedbarium, magnesium, etc but it will be under-- stood that any compoundsother than the alkaline earth metal hydroxides mentioned herein, whichare capable of bringing about the reaction on the sodiumsoap compoundsin the manner described are included within the spirit of thisdisclosure. vNor is this disclosure limited in the practice to thepreliminary treatment with an alkaline solution and then with an agentthat will convert the soap forming oil soluble compounds intooil-insoluble compounds. While it is preferable to segregate thesepractices, and to perform them in accordance with the teaching of thisdisclosure, it will be understoodthat the treatment of the oil withagents that will convert the soap forming compounds into oil insolublecompounds may occur concurrently with the treatment with the weakalkaline solution, and that the caustic soda treatment may be omittedaltogether, because our experience shows that substantially the sameresults may be obtained by treating the oil directly with an alkalineearth metal hydroxide,

although the results desired are more diflicult to obtain than by thecomplete process as outlined above. 4

What we claim, is:

1. In the treatment of hydrocarbon oils to free them of emulsifyingcompounds, the

process which consists in treating the oil with a relatively weakalkaline solution under pressure and agitation with live steam,separating the aqueous solution from they oil;

and in then removing the soap forming compounds by converting them intooil-insoluble compounds, adding clay to the oil thus treat ed and thenfiltering the oil.

2. The process of treating lubricating oil to remove emulsifyingconstitutents which consists in mixing with the lubricating oil arelatively weak caustic soda solution, 1n subjecting the mixture to asuper-atmospheric pressure, in agitating the mixture with steam; inpermitting the mixture to settle,

and in removing the aqueous portion'of the 4 mixture; and in thenremoving the soapforming compounds by converting them into separableadsorptive compounds, involving mixing with the oil thus treated analkaline treated oil with an alkaline earth metal com-= pound and anadsorbent clay at a temperature of approximately 300 F. and finallyseparating the purified oil from the alkaline earth metal compound, andabsorbent clay contain ing the emulsifying constituents.

4. The process of removing emulsifying constituents from lubricatingoils comprising commingling the oil with a water solution ofcaustic sodacontaining not more than three and one-half per centum of caustic sodaand in quantities sufficient to neutralize and combine with all theemulsifying con stituents'contained in the lubricating oil,agitating-the mixture of lubricating oil and caustic soda solution withsteam under pressure greater than atmospheric, separating the aqueoussolution from the oil, then commingling the separated oil with a mixtureof calcium hydroxide and an adsorbent clay at a temperature above theboiling point of water, and finally separating the purified oil from thecalcium hydroxide and adsorbent clay together with the emulsifyingconstituents.

5. In the treatment of hydrocarbon oils to free them of emulsifyingcompounds, the process which consists 'in treating the oil with arelatively weak alkaline solution under pressure and agitation with livesteam, separating the aqueous solution from the oil, adding an alkaliearth metal hydroxide and an adsorbing agent to remove any remainingemulsifying constituents, agitating and heating the mixture until thewater is expelled, and then separating the purified oil from the ihydroxide, adsorbing agent and emulsifying constituents.

In testimony whereof we have set our hands.

JOHN C. BLACK.- WIRT D. RIAL. RAYMOND T. HOWES.

